Why Bridges Move...
HTML-код
- Опубликовано: 5 окт 2024
- ...and other musings on thermal movement of large civil works.
Most people have a certain intuition about thermal expansion, but you may not have considered how engineers design to accommodate it on large civil structures. The video gives a quick overview on this important consideration that engineers must account for when designing infrastructure like pipelines, bridges, and even sidewalks.
Watch this video and the entire Practical Engineering catalog ad-free on Nebula: go.nebula.tv/p...
-Patreon: / practicalengineering
-Website: practical.engin...
Marxist Arrow by Twin Musicom is licensed under a Creative Commons Attribution License
Source: • Marxist Arrow - Twin M...
Tonic and Energy by Elexive is licensed under a Creative Commons Attribution License
Source: • Elexive - Tonic and En...
This video is sponsored by Blue Apron.
"It's a little hard to show on camera."
_Show's an excellent, clear visual of the bridge buckling side to side._
Darth Obscurity I can see it more than cctv in banks
*sigh* everytime I do a joke like this someone just says "Yeah, HE MEANT TO DO THAT.".
Jeez.
I ruined the perfect 666 likes 😌
He lied to us
@@AliShah-xm2jf Ok, and
I first learn about thermal expansion when I was pretty young: I was heating a glass of milk in the microwave but forgot to put the milk. When the microwave finished I realised i had forgotten the milk and I though: "I guess I'll put the milk now"
And as soon as the milk touched the glass it exploded.
R.I.P Glass of milk, 2019-2019
@@arijitdubey2282 wrong year
He said *when he was younger* not "this year".
Read the comment 🤦♂️
I use to heat water in glass in microwave for storing in thermal bottle. After filling & empty same glass for more than 5 times, glass cracked while filling room temperature water.
@@amitkrupal1234 Savage temp. cycling! ;) I have heated a lot of glasses of water in microwave safely, but without cycling. Once, however, I poured very little water and microwave overheated it. The glass has cracked at the base, but crack was not catastrophic and it is still in one piece ;) Glass cracks really quickly, as crack propagates with speed of sound in the glass. It is crazy fast, much faster than speed of sound in the air.
This video felt like it took forever to explain what I knew when I was 10
Might as well re-title the video, "I needed an excuse to buy a spot welder." We all know the truth.
hahahahahahahahaha good one
John Alexander yeah i want one too now lol
@John Gault I came up with the desire to build a spot welder. I got all the parts and had made the transformer and enclosure, but needed a good excuse to finish it. So I built an electric bike, and needed to finish it to weld 252 batteries together.
It took a bit of tuning of the jig and electrodes to get it welding good, but was a fun project. I like when I can combine different hobbies such as woodworking, metal, and electronics. Now I work with welders for a living, so it was a fun intro.
or to show off his wife.
Which temp effects bridge to collapse.
This channel is honestly making me consider switching from mechanical engineering to civil. I’ve started to find it so much more interesting, particularly traffic and transportation engineering and especially because it’ll be a stable market
Ah temperature, mortal enemy of all engineers.
well no
@@axye1024 Jk
Axzye Spies?
Im honna disagree and say soil and or leaks are engineers worst enemies
Well, it is also the best friend for good engineers.
I love your videos. I love how you explain them. Not boring graphs and things that make sense. I'm not saying that graphs are bad but sometimes they are overused.
I watched a show about building a large bridge. The bridge was being built from both sides and had to meet in the middle. When the last pieces were being bolted together in the middle they had to wait for the bridge to reach a certain temperature so the bolt holes would line up. You could see on camera that the bolt holes were slowly lining up as the bridge warmed up.
That sounds awesome, I'd love to see that! Do you remember which show it was?
Dude that's sick 👌
What show is this??
did they use a hair dryer?
ok, ok, maybe not a hair dryer. maybe 100 hair dryers?
Anti-clickbait.
The answer was in the thumbnail itself.
I love you.
In aircraft maintenance we have to take temperature into account when doing things such as setting control cable tension. As the expansion rates of the aluminum structure and steel cables is sufficiently different.
Not to mention huge temperature shifts.
A bridge is just a street that's high.
So simple but true.
“Yooo dawg, Im a bridge and im highhhhh”
@@awhahoo I- 🦕🤚🏻
Yeah, you can get drugs almost anywhere these days
Who would win?
Millions of pounds of steel and concrete
Or...
One warm boi
I've seen a motorcycle kickstand sink into asphalt in a parking lot.
Clumsy #DDM
*A H O T T Y 🅱️OI*
@@nicolasknoester7628 son😂😂
jet fuel
I studies two of years of civil engineering and we learned some of this or that, but the way you explain things make them look very easy to remember and learn.
Fun fact, in countries without much temperature fluctuation (like Philippines, or any tropical countries), they don't bother with expansion joints.
You will see whole stretches of highways with no cracks, just smoooooth driving.
That is of course if there wasn't so much traffic here in Manila
ice is one hell of a thing.
ehh you're right they don't bother with it
but they still get a lot of cracks from other factors
i thought asphalt still becomes more fluid/squishy in the heat and then cools at night
Bullshit! I live in philippines and i see alot of road cracks.
I like how you have an ad at the end. That's how all videos should be, ad at the end, so you aren't forced to skip through it and you can still let it run at the end if you liked the video and want to support the channel.
"That's a great smile, honey, but could you do it a little more to the left so I can see those cool expansion slots behind you." - Things you don't want to say on vacation.
I had to read that a second time to make sure what you said is what you intentionally meant ( ͡° ͜ʖ ͡°)
krtwood U8
😂
Sorry I'm autistic and retarded. Would anyone mind explaining what this joke is about straight forward?
He used pictures from a vacation with his wife as examples, and she's sort of in the way 5:43. Telling her to move would be good photography but bad husbandry. Damn funny.
As a civil engineer, and builder, I know this all too well. Great job making a simple yet complex topic fun and engaging. I learned something here and hope others do, too’
The road expension zones on Bridgers make a really satisfying *Thunk* when you drive over them too.
I've seen joints on bridges that had big rubber seals in the gap, presumably to smooth out the transition. When I was a kid, it puzzled me to no end.
i studied civil engineering in a great university and i hated it from the start and then i quit the university, and now i see the problem i was the teaching problem that we'd suffered. You do a great job keep on doing that people need this
Every day’s a good day when there’s a Practical Engineering video.
LegendLength it doesnt matter unless it happens to be you
Every day's a good day when i don't wanna die.
I wish you went into a bit more detail on the specific techniques used to compensate for thermal expansion. Some of the contraptions in the photos you showed looked really interesting.
Great explanation, same principles take place in precision machine building.
I admire the mind of engineers who can also talk in layman's terms like this video. I'm sure machinery taking into account the heat produced without "leaking" power would be interesting to hear :)
Wood carpentry too, though moisture is usually a bigger issue than temperature.
When our local bridge was being renovated, I was really irritated about the heavy traffic that it caused. Once the bridge was opened, I saw those teeth like structures in the thumbnail. I didn't know what they were for. Perhaps they were meant to protect the people passing through that bridge in the first place. Now we know heavy traffic would be the least of our problems if the bridge wasnt renovated. Thanks for the awesome video. 😀
These teets are used to feed bridge troll to keep him happy.
You are amazing Brody. I'm studying civil engineering at an Ivy League University, with all their resources and Nobel laureates, and hands down I'm learning more from you than I do from them. You rock.
Rolls-Royce Trent Engines us this to thier advantage. The Turbine blade tip clearances are controlled by a system called TCC or Turbine Case Cooling. This shrinks the case during steady state, closing the tip clearance, increasing the efficiency of the turbine
Actually some race and high performance engines are built in a way where they have loose fit when cold and sealing up when warmed up. Or like Formula 1 engines: They are basically seized up when cold and must be warmed up to clearances to appear.
The most common application would be the thermostat. You can find it on most home appliance dealing with heat.
The SR-71 Blackbird spy plane would come back leaking fuel all over the place and would have to be repaired after every mission because of the heat from supersonic flight.
At demolition derbies it is common for the real pros to bore out their engines to a slightly larger inner diameter than the pistons. it leads to the engines shooting occasional flaming smoke rings (that look really cool) early on, to getting tighter and more efficient as the round wears on. As everyone else engines begin to seize, these guys hit their maximum output. Strategically and technically brilliant.
@@edwardschmitt5710 SR-71 was designed to leak while parked. The plane expands in flight and the tanks seal up. It doesn't leak in flight once it reaches operating temperature.
I think every High School in America Needs you teaching classical physics and engineering principals, yours are excellent quality tutorials. Thank you
in California, we also have to have room for systemic movement as well as thermal and take into consideration slow tectonic plate movement too. good info Grady
In San Francisco it had to be a very difficult work to maintenance all of the linear infrastructure because of all of these slip-strike faults.
Plus an additional five or six hours for the PE in California for seismic, I think
Cali sucks
Good luck with the big one, Americans
Careful now. Anything in the state of California is carcinogenic. But only to Californians.
I'm a civil engineer, and this is hands down the best science channel on youtube. Congrats!
Woah, hang on... You mean to tell me, that you do calculations in both Metric *AND* Imperial?!
I'm so glad ThisOldTony brought me here!!!
hahahahaha SI UNIT JOKEZZZZZZZ
You can also hear thermal expansion when you turn on your oven and the opposite (thermal contraction) when you shut your car off the exhaust manifolds make a clicking noise as it cools down. You can hear it in the plumbing when you turn the hot water or duct work when the heat comes on. Sometimes older homes pop and creak as temperatures change outside. I’ve always found this fascinating.
Another good example of engineers overcoming thermal expansion can be seen in the SR-71. The plane will actually leak fuel through the wings when at sub sonic speeds because of the clearances put in between the edges on the outer panels. When the plane reaches its max speed or close to it, the air resistance creates enough heat to cause the outer panels to expand. The clearances allow for the expansion to take place without a dangerous build up of unwanted stress.
isnt the heat generated due to compressing the air and not because of air friction?
@@Blox117 no, the parasitic drag (air friction) is far more effective at heating the plane itself. Air compression will heat up the surrounding air, like with spacecraft re entering the atmosphere, but the metal itself is heated from the friction.
Hey Grady, great video. I know you were only addressing movement due to thermal expansion and contraction, but we also have to allow for rotational movement due to live load deflection. Moveable bearings allow for longitudinal and rotational movement while fixed bearings only allow rotational movement. I stumbled across your channel this week and I am enjoying it. Even after 36 years in the profession there are many areas of practice that I have rarely been involved with and your videos are great refreshers.
Great topic! You have the best mix of animations, real world examples, and DIY experiments! Love it!
And don't forget using metric and imperial side to side!
Loved the video. I am a carpenter/ bridge builder in Arizona. I also grew up near the cat walk in southern New Mexico. 👍👍👍
As a Mechanical Insulator I can appreciate this video, since I need to account for a pipe's thermal expansion in some applications. Especially in refractory and cryogenic systems.
What local?
Local 118
Nice I started in 118
What year are you
I've got lots of hours, but I'm in 3rd year school now. Small world lol...well I say that but this is the internet.
I love this channel. Everything I've ever thought about while driving or glance that and wondered what or how, you have answered. Thank you
I always stare at the spans on the bandera overpass waiting for the light at 410 thinking man if that slides off were done for. As a fellow San Antoninan. Love your videos man!
I knew some of this stuff before since I worked in construction but to get more detail of it was just awesome. Thank you for the more specific details.
I never knew that was why sidewalks were sectioned. I always just assumed it was a bi-product of the construction process.
Now I know why some older highways are sectioned, and why causeway bridges are sectioned.
Same here, I can now understand why the roads in a certain part of my country are all sectioned like that, because that area has insanely high temp fluctuations compared to where I live. :)
Sidewalks are built like that because concrete shrinks as it cures. Basically masons define "cracks" before the concrete finds its own cracks.
Installed some steel railings on concrete a few years ago. About 100 feet long, one piece. The crew at the time remarked that it should have some expansion joints, but the customer said to do it anyway. 6 months after I got a call that our anchors had failed. After taking some pictures I was able to prove that they had, in fact, sheared. Not a warranty fix. So they paid me to upsize all the bolts massively.
A buddy of mine was nearby when it failed. Catastrophically. the pressure built up until it blew off the concrete and sent shrapnel through all the walls and ceiling. According to my buddy they jumped literally 4 feet in the air. It had been planned and engineered, and my work was to plan. Got paid to re install it with some expansion joints.
I've since encountered a lot of incompatible materials embedded into concrete, leading ultimately to failure. Surprising that there are engineers and architects out there who don't know about this.
Man I just love your channel
Know about thermal expansion since I was a kid but never thought of the real world implications or workarounds! Brill video!
RIP to all the undergads in Thermodynamics this semster
Japhet Ye hahahahahahahaha ain't that the truth!
F
F
I had Gandalf as my instructor. Favorite line was "You Shall not Pass!".
The two wires of a thermocouple must each act as an I N F I N I T E F I N
A little late to the party but this is the first channel i saw with engineer orientented concepts, wonderfull animations, calculations in both imperial and metric and also with diy experiments, you have won a subscriber
Thermal expansion of bridges is quasi-static, I'm still very disturbed by the fact that civil engineers study dynamics ;)
Jeff Irwin is this english
Static in length, dynamic in loading.
+Sparks no, it engininglish
Take a look at Burj Khalifa (Wind design), the Taipei 101 (Typhoon design), or Sales Force Tower (Earthquake Design), then only will you appreciate that civil engineers study dynamics. In reality much of what we do as structural engineers involves vibration, seismology, wind tunnel testing and a whole lot of dynamics.
laith elayyan It's a field where there are still discoveries to be made. Hopefully more in a test lab than in the field.
Nice video. I’ve been a commercial construction project manager and superintendent for over 30 years and never considered expansion joints as thermal control devices. We’ve installed then for sub-terrenan movement. Interesting...!!
Biggest one to notice if you've ever done it, vinyl siding, if you don't keep the fastener a bit loose and center it in the slide, you'll end up with warped broken pieces.
I'm a amateur civil engineer and I really didn't know why roller supports are used. You helped me a lot mate thanks. You gained a sub
I saw another video on youtube by a mason titled: Building Brick Walls (Old School vrs. New School) Mike Haduck. He said that modern buildings with rebar are only built to last 35-50 years and showed a piece of rebar that had rusted away a substantial portion of its mass. He was saying that brick walls built using the older way with more brick last a lot longer. Maybe you could comment on the longevity of rebar and how it holds up to oxidation.
Also have that question. Also saw that video. :)
Not really a fair comparison because rebar is used to give concrete tensile strength. It's not serving the same purpose as the brick. If you placed a solid concrete wall to the same dimensions as a brick wall, I think they would last about the same. e.g. Hoover Dam was built in 1931.
> Mike Haduck
Thank you, subscribed.
the steel reinforcement rusts because concrete has micro pores which allows water to seep in. the concrete and brick holds water like a sponge. technically if you could cover the steel with a passive oxide layer like stainless steel has, it would last forever.
michaelg uhhh, no only when its new. thats why the steel rusts after a few years.
I'm a civil engineer myself, so nothing new for me here. But I just enjoy watching these videos so much! Thanks Grady!
The clockmaker John Harrison (of Longitude fame) recognised this as a key problem in accurate timekeeping and invented the Gridiron Pendulum to compensate. Are there examples of that in structures though or just clocks?
buildings rarely need to expand a set amount at a specific time
The point of his design was that Harrison used clever engineering so that even when the metal expanded due to heat, the pendulum would remain the same size and the clock's timekeeping would remain precise. A pendulum getting longer slows clocks down and if you have a grandfather clock, you have to rotate the weight to raise/lower it throughout the year - the winter/summer temperature difference has a surprisingly large effect
Excellent video. Something we all should learn about since we drive everyday over bridges and roads
me: never seeing that equation before, stumped!
but understand everything else...
wife: "oh yeah i know what that equation is..."
but doesn't understand how and why
teamwork makes the dream work!
Didn’t know what the equations was at all. Recognized the symbols. Ahhh I understand. Triangle = delta = ‘a change of ___’
Thank-you math
Speaking of which, what was the exact formula?
I always didn't understand why there are those connection gaps on bridges and now i know. Great Video!
You got to be a civil engineer to enjoy holiday pictures because of the bridges instead of the people.
It depends of the type of people you know.
screw the people. throw them off of my bridge
usually the people you are on holiday with are people you can see often
but the bridges you see on holiday you won"t have at home
Slowly working my way through playlists and when you explained the expansion joints in a sidewalk I literally sat up and said "OH!"
I've seen those things all my life and even watched a crew take out a section of sidewalk in front of my grandmother's house (and then replace it of course) and still had no idea. Neat!!
moral: build everything out of diamond
Every object thermally expands, good conductors like metals expand faster that's all.
I get its a joke, but diamond is fairly brittle, and thus, would make a terrible building material. That is not even accounting for the fact there are no diamonds big enough to build anything with.
I'm pretty smart but in no way an engineer or even a college graduate, but now I'll be keeping an eye out for thermal expansion joints and slides any time I'm around a large structure. Thank you for the info.
What about long pipelines?
as Ufasdfgewaf said and also they are under ground so the temperature is mostly constant throughout the year...
What about the Hype-loop?
they're probably going to use slip joints in the hyperloop if it's above ground. you can't have tight bends in that can you
long pipelines usually have large U sections to allow some expansion
Russel Walker expansion loops or expansion joints (corrugated metal bellows)
James Bradwell it will be build using slip joints as steven yau said and will be held on slip holders/mounts... watch the Thunderfoot video when he visited the hyperloop... tho i am also skeptic about the hyperloop...
Thank-you for solving the expansion segments in the sidewalk that I was thinking about two days ago.
Thank you for explaining thermal expansion to us in a easy to understand way. We really appreciate your work!
3:09 this channel is a legend, they add the formula for both measuring system
"We often think of Civil Engineers as designers of Targets"
--The Airforce
Very informative. Having learned these things in school it's still useful to be reminded of them. Thank you!
Make a video about how engineers protect and maintenance infrastructure against tectonic motions.
I don't know how did this came to appear in my suggested videos but you definitely earned a subscriber. Great work!
How does large boats do it?
But the hull is not constrained outside. Thermal tension is a problem when you have constrain something.
You want to know what I think??
I think you provide a wonderful explanation of engineering concepts that everyone from a complete novice to an experienced professional can appreciate and learn from. The fact that you and others like you provide this kind of quality content for free is extraordinary and I hope you keep up the great work inspiring the next generations of engineers.
That's what I think.
"Here we are on vacation. Here's a photo of my lovely wife. Look at that bolted bracket on the left and the slides to allow expansion!" LL, spoken like a true engineer! 😁
the go-to channel when youtube just gets too vapid. love this guy.
Yay lovely to see the Sydney harbour Bridge hinge! Largest hinge in thr world. Would be very interesting to American viewers to see the scale of how that double hinge let's the metal arch grow a couple metres in the summer.
Excellent. Again thanks for sharing and thanks to whom sponsored this video
2:10 ‚it may look complicated‘
All engineers start laughing 😂
Worked at a large hospital where they added 3 3megawatt diesel generators during an expansion project. Generators were located in basement and went up inside if building for 10 stories or at least 150'. As soon as they started first generator they had reports of noise and banging metal. Brillant engineers never installed expansion joints in 3' diameter exhaust pipe that had temperatures over 750 degrees F. Had to rip out triple sheet rocked walls to refasten exhaust pipe. While doing same project engineers did not install what we were told less then a $100 In something for outside drains. Within a year or so water leaked into several basement offices. They had to relicate several offices to remove damaged sheet rock a lot of ceiling titles and carpets then dig up parking area to correct the problem. Both cases enhineers tried to pass the buck. Said contractors should have caught it but contractors said they went 100% by plans. Another time they installed a 36" chiller water valve handle in place where wall was going to go. Forget how many thousands of dollars that goof up fix cost. They had to drain system on a weekend then remove at least 96 bolts to rotate valve 90 degrees.
I'm surprised and disappointed by the lack of your trademark googly eyes on the demo bridge.
How about a video about other ways certain kinds of bridges are designed to move (drawbridges, lift bridges, among others)?
great video, thanks
great comment, thanks
great greats, thanks
thanks
great thanks, thanks
thank greats, great
I don't understand how 1000 people took the time to hit the dislike button. This was educational, informative, and gave great real-world examples. If you're uninterested, just keep moving along. Just needed to rant. I'm a mechanical aerospace engineer who appreciates your content. Keep on doing what you're doing! Wish these videos were around when I first started my degrees.
They are trolls with nothing else to do all day, living in mummy’s basement with no job to go to.
Why was this under “recipes”?
Great video and greatly appreciated the fact that you put up calculation in SI unit as well for global audience.
"You are likely already Familear with Thermal Expansion"
With the Minecraft Mod, Yeah.
I was looking for this
I just want to say how much I appreciate your work. Your dedication to teaching is awesome! Thank you :)
I'm thinking of being a civil engineer when I'm older but I don't know what qualifications I need
Please like this so that he will see it
You need to get a bachelors degree in civil engineering and then get licensed.
Wonderful video, excellent description and demonstration of thermal expansion and contraction. Excellent bridge and side walk examples.
Great video, as always. When you're talking, you sit a bit too close to the camera, causing the top of your head to get cut off. That's aesthetically unpleasing. Just a minor complaint but I hope you fix it in future videos. :) Also, thermal expansion isn't usually considered while designing buildings. I suppose that's because generally, buildings don't have dimensions large enough for thermal stresses to get significant.
Building walls do have expansion and contraction joints placed in them. Typically you will see them at around 50' spacing or less in masonry walls.
+Michael Onines Oh wow. I didn't know that. Hmm what about framed structures though?
Feynstein 100, the frame inside the building stays at a relatively constant temperature, so it isn't as big of a deal. For roof beams above the insulation you use detailing that allows for connections to move a little bit. It's an issue I've seen cause problems if it isn't addressed correctly in the detailing.
+Michael Onines Oh okay. That's not part of the building code around here though.
The SI and Emperial Units side by side was greatly appreciate.
Hi
You anti clickbaited us, ask a question in the title and answer it in the thumbnail. Nice!
THANKS MR ENGINEER you helped many lives of engineer students with this video
Watching talk about the ways engineers work with thermal expansion at @5:30 reminds me of some of the stuff steam locomotive manufacturers came up with to handle thermal expansion.
I know nothing about engineering but I do love watching videos about it. It's all very interesting
I got stuck in grand haven Michigan’s draw bridge, probably about 5 cars back from the stop poles that come down. It was an extremely hot day, it drew open for water traffic and then it wouldn’t close. Thermal expansion. They had to hose it down and I remember thinking at the time “yeah that’ll fix it” sarcastically…. But it did.
One summer day in our newly made office we saw great demonstration of this phenomenon. Our long straight gallery floor (70m maybe), was covered by ceramic plates during the winter, that plates poped up in the middle at 10cm!
Your video is #45 Trending! Thats amazing, I knew after your tuned mass damper video you would make it big if you kept up the good work! Congratulations
I always thought the breaks in sidewalks were to help with laying them or repairing broken sections without having to rip it all up. I never even considered they were wiggle room for shifting but that actually makes a lot of sense. Thanks for the breakdown!
Im a 4th yr civil engineering student, your videos are being presented to us by our teacher
wow. I had no idea that this had such a huge effect and needed to be taken into account in construction. Amazing
It’s really interesting, I’m learning some of these concepts in mechanics of materials
I knew some of this, but you taught me a little about pre-stressing, which I think is really cool.
Great video . Didn't realize such a thing happened with bridges or any other structures in general.
Every time I watch your videos I just want to subscribe again and again and again